Pallet

ABSTRACT

A pallet which is made from elongate steel members of arcuate cross section which are welded together to form a frame, and plastic slats which are engaged with a snap action with the steel members and which form a planar upper surface for the pallet.

BACKGROUND OF THE INVENTION

This invention relates to a pallet.

Pallets have traditionally been made from timber. The use of timber in aworld which is increasingly sensitive to ecological factors, is becomingunacceptable. Timber also carries with it the risk of transferringdiseases and insect pests, a danger which is compounded by the use oftimber pallets in international trade.

As an alternative to timber pallets is known to make pallets from aplastics material. Thermoplastic materials, which are recyclable, dohowever display a number of disadvantages such as an unfavourable costto strength ratio, the existence of a creep characteristic which leadsto an over-design situation with a resulting higher cost, and therequirement to make use of flame retardants, which are expensive, tominimize fire hazards. Thermosetting plastic materials on the other handare not recyclable and, generally, are subject to slow and costlymanufacturing techniques.

All-steel pallets have been used but have only enjoyed limited success.Steel pallets are heavy and consequently are expensive. In an attempt toaddress the weight problem it has been proposed to make pallets frommesh, eg. welded wire mesh. A problem which arises in this connection isthat it is difficult to achieve a predetermined ratio, of the order of40%, of the bottom surface area to the upper surface area of the pallet.This is necessary to reduce stress concentrations when pallets arestacked one on the other.

It has also been proposed to make use of recycled rubber which is bondedto steel sections to make a composite pallet. The resulting constructionis however heavy and can be expensive.

A need exists for a pallet which does not host insects and which isrelatively inexpensive, robust and with good loading characteristics.

SUMMARY OF INVENTION

The invention provides a pallet which includes a frame formed by aplurality of elongate metallic elements, and a plurality of slats whichare engaged with the elements.

The slats may be engaged with the elements to form a substantiallyplanar upper surface and a lower support surface or surfaces.

The slats may be made from an appropriate plastics material for exampleby means of a moulding process.

The slats may be engaged with the elements in any appropriate way andpreferably are engaged with a snap fit with the elements. To achievethis the slats and the metallic elements may include interengagingcomplementary formations.

Each slat may be of any appropriate size and shape and, in a preferredexample, each slat has a planar upper surface with a plurality ofunderlying reinforcing ribs or similar formations. To reduce weight andthe consumption of material each slat may be formed with one or moreopenings.

Each slat may be made from any appropriate material such aspolyethylene, polypropylene or polyurethane. The choice of materialdepends however on a number of requirements including cost, durability,weight, resistance to ageing and the like. The scope of the invention isconsequently not limited by the choice of material.

The upper surface of each slat may be roughened, in any appropriate way,to display a desirable coefficient of friction. This helps to ensurethat a product placed on the slats remains in position. The uppersurface may be sandblasted but preferably is moulded with a roughenedupper surface defined for example by small projections on the uppersurface.

Each elongate metallic element may have any appropriate cross sectionalshape. In a preferred form of the invention though each element has anarcuate cross section ie. concave and convex outer surfaces. The arcuatecross section of the elongate metallic element may subtend anyappropriate angle which may vary according to requirement and whichtypically is in the range of from 150° to 170°.

Within the frame the elongate metallic elements are oriented to providemaximum strength. Each elongate metallic element is preferably orientedso that its width is positioned in a vertical orientation, in use of thepallet.

Preferably each elongate metallic element is made from high tensilesteel.

The elements may be secured to each other in any appropriate way and forexample are fixed to each other by means of welding.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described by way of examples with reference tothe accompanying drawings in which:

FIG. 1 is a perspective view of a full perimeter base pallet accordingto the invention,

FIG. 2 is a perspective view of a skid-type pallet made using theprinciples of the invention,

FIG. 3 is an enlarged plan view of a portion of a pallet according tothe invention,

FIG. 4 is a cross sectional side view of the pallet portion shown inFIG. 3 taken on a line 4—4, and

FIG. 5 is a cross sectional view of the pallet portion shown in FIG. 3taken on a line 5—5.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2 respectively illustrate a full perimeter base pallet 10and a skid-type pallet 12 made, in each instance, using the principlesof the invention. Overall the pallets 10 and 12 are substantiallyconventional in appearance although it is to be noted that each palleton an upper surface has a tile-like or slat-like appearance.

FIG. 3 is a plan view of a portion of the pallet 10, on an enlargedscale. It is to be understood though that the following descriptionapplies equally to the construction of the pallet 12.

FIGS. 3, 4 and 5 illustrate a plastic slat 16 which is engaged withspaced steel elements 18 and 20 respectively.

The slat 16 is one of a plurality of slats, see FIG. 1, which make up asubstantially planar upper surface 22A of the pallet 11 and which aredesignated 16A, 16B . . . 16N respectively. On its under side 22B, notvisible in FIG. 1, the pallet 10 also has a number of slats which facedownwardly. The number of slats on the underside is substantially lessthan the number of slats on the upper side.

Each slat is moulded from a suitable plastics material such aspolypropylene. The slat has a planar upper surface 24 which is roughenedby means of integrally moulded projections 25 so that it possess asuitable coefficient of friction, downwardly depending sides 26, and aplurality of reinforcing ribs 28 on its underside. Elongate slots 30 areformed through the planar surface of the slat at regular intervals. Thisreduces the weight of the slat without compromising its strength.

The sides 26 of the slat are arcuate in shape. The side on the right inFIG. 4, designated 26A, has a concave outer surface while the side onthe left in FIG. 4, designated 26B, has a convex outer surface.

The elements 18 and 20 are made from high tensile steel. It is apparent,particularly from FIG. 4, that each element has an arcuate cross sectionwith a convex outer surface 32 and a convex inner surface 34. The innerand outer surfaces subtend an angle 36, at the centre of curvature,which lies between 150° and 170°. A typical value is of the order of150°.

The steel elements are welded to each other in a lattice-typeconfiguration to form a frame. As far as is possible the elements areoriented, as shown in FIG. 4, so that the width 38 of each element is ina vertical orientation. The elements are spaced from each other by adistance 40 which is effectively the width of a slat 16.

Referring again to FIG. 1 the elements, on the sides of the pallet, arespaced to define openings 42, of predetermined dimensions, which allowthe ingress of forks of a fork lifter or similar appliance so that thepallet and its load can be handled. A similar observation applies to theskid-type pallet 12. These aspects are however known in the art andconsequently are not further described in detail.

The construction which has been described for the upper side 22A of thepallet applies equally to the lower side 22B although, as noted, thenumber of slats used on the underside is significantly less than thenumber of slats used on the upper side. To ensure that stressconcentrations, in use, do not exceed predetermined maximum values, thetotal surface area of the slats on the underside should be at leastapproximately 40% of the total surface area of the slats on the upperside of the pallet.

In order to form the steel frame the steel elements are placed in a jigand are then welded to each other using any appropriate weldingtechnique eg. robotic welding. The resulting frame is then galvanised orotherwise protected against corrosion. The slats 16, which arepremoulded, are then engaged with a snap action into the respectiveopenings formed in the steel frame. Each slat engages with the steelframe in the manner shown in FIG. 4. Once all of the slats have beenengaged with the frame the pallet is ready for use.

The pallet of the invention has a number of benefits. Through suitabledesign the pallet can be constructed to take a load of up to two tons.This compares favourably to the loading capacity of a conventionaltimber pallet which is typically of the order of 1,5 tons.

The composite steel/plastic construction is inert to insects and has agood strength to mass relationship, has a long life, can be recycledwhen necessary, and is not subjected to splintering or rotting. Althoughthe pallet can be recycled it has minimal scrap value. This reduces itsattractiveness as a theft target.

The ratio of the mass of the pallet to its load carrying capacity issignificantly better than the corresponding ratio for a timber pallet.

The pallet does not display creep with time or temperature under normaloperating conditions and it can be manufactured in large volumes. Thepallet can be refurbished when necessary simply by replacing brokenslats or by welding or replacing damaged metallic elements, as the casemay be.

The steel elements are, wherever possible, oriented so that the width 38of each element is vertical. However to allow the forks of a fork lifterto enter the apertures 42, without snagging, rounded surfaces of theelements may be used to define perimeters of the apertures, or othersteel members may be used.

1. A pallet which includes a plurality of elongate metallic elementswhich are secured to one another to form a frame, each element havingconcave and convex outer surfaces, and a plurality of slats, each slathaving two opposed sides which are respectively convex and concave andwhich are engageable, with a snap fit, with respective concave andconvex outer surfaces of two adjacent elements.
 2. A pallet according toclaim 1, wherein the slats are engaged with the elements to form asubstantially planar upper surface.
 3. A pallet according to claim 1,wherein the slats are engaged with the elements to form a lower supportsurface or surfaces.
 4. A pallet according to claim 1, wherein the slatsare made from a plastics material.
 5. A pallet according to claim 1,wherein the opposed sides of each slat includes formations which arerespectively complementary to the concave and convex outer surfaces ofthe elements.
 6. A pallet according to claim 1, wherein each slat has aplanar upper surface with a plurality of underlying reinforcingformations.
 7. A pallet according to claim 1, wherein each slat isformed with one or more openings.
 8. A pallet according to claim 1,wherein each slat has a roughened upper surface.
 9. A pallet accordingto claim 1, wherein the concave outer surface of each metallic elementsubtends an angle which is in the range of from 150° to 170°.
 10. Apallet according to claim 1, wherein each elongate metallic element isoriented so that its width is positioned in a vertical orientation, inuse.
 11. A pallet according to claim 1, wherein each elongate metallicelement is made from high tensile steel.
 12. A pallet according to claim1, wherein the frame is formed by welding the metallic elementstogether.